.\"-
.\" SPDX-License-Identifier: BSD-2-Clause
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.\" Copyright (c) 2020 Gordon Bergling
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.Dd April 27, 2020
.Dt UNIONFS 4
.Os
.Sh NAME
.Nm unionfs
.Nd union mount file system
.Sh SYNOPSIS
To compile this driver into the kernel,
place the following lines in your
kernel configuration file:
.Bd -ragged -offset indent
.Cd "option UNIONFS"
.Ed
.Pp
Alternatively, to load the driver as a
module at boot time, place the following line in
.Xr loader.conf 5 :
.Bd -literal -offset indent
unionfs_load="YES"
.Ed
.Sh DESCRIPTION
The UNIONFS driver is an implementation of a stackable unification filesystem.
.Sh SEE ALSO
.Xr mount_unionfs 8
.Sh STANDARDS
.Rs
.%T Union mounts in 4.4BSD-Lite
.%A J. S. Pendry
.%A M. K. McKusick
.%R Proceedings of the USENIX Technical Conference on UNIX and Advanced Computing Systems
.%D December 1995
.Re
.Pp
.Rs
.%T Jails: Confining the omnipotent root
.%A P. H. Kamp
.%A R. N. M. Watson
.%R Proceedings of the Second International System Administration and Networking Conference (SANE2000)
.%D May 2000
.Re
.Sh HISTORY
The
.Nm
device driver first appeared in
.Fx 5.0 .
.Sh AUTHORS
.An -nosplit
The
.Nm
device driver was written by Jan-Simon Pendry for
.Bx 4.4
and
.An Masanori OZAWA Aq Mt ozawa@ongs.co.jp
reimplemented the handling of the locking for
.Fx 7.0 .
The manual page was written by
.An Gordon Bergling Aq Mt gbe@FreeBSD.org .
.Sh BUGS
Please see the
.Xr mount_unionfs 8
manual page for a list of bugs regarding the
.Nm
filesystem.
